RISK-FACTORS FOR NEISSERIA-MENINGITIDIS CARRIAGE IN A SCHOOL DURING ACOMMUNITY OUTBREAK OF MENINGOCOCCAL INFECTION

As part of the management of an outbreak of meningococcal infection, 1 19 school contacts of an index case were swabbed for nasopharyngeal ca rriage. In a cohort study, risk factors for Neisseria meningitidis car riage were ascertained by means of a questionnaire, completed by 114 ( 96%) of those swabbed. Twenty five (21%) cultures were identified as ' neisseria positive'; of which there were 18 (15%) Neisseria meningitid is isolates, 2 (2%) Neisseria lactamica isolates and 5 (4%) showed con taminants only. Two (2%) carriers were identified as harbouring the im plicated outbreak strain. Single variable analysis identified six stat istically significant risk factors for meningococcal carriage; increas ing age, female sex, manual social class, personal smoking, regular at tendance at a discotheque and rhinorrhoea. Multivariate analysis, usin g logistic regression modelling, found that of these six variables onl y age, sex and social class remained statistically significant when th e other factors were controlled for. Nevertheless the role of smoking, social events and respiratory/viral infections in nasopharyngeal carr iage, and other plausible mechanisms whereby age, sex and social class might exert their effect, could usefully be investigated further.